In May 2012 a hitherto unknown US think tank the Center for National Policy (CNP) published a short paper on a strategy for NATO; one of the co-authors is Ryan Evans, whose work I have cited before.

From the summary:
The main elements of this plan, some of which are already in place, are as follows:

• Continue transition plans to place Afghan Government and Security Forces in the lead across the country by April 2013. However, “transition” must take on more substance than it has so far. The April 2013 transition cannot be a political fig leaf for home audiences, but an end to American and Allied (non-Afghan) combat operations against Afghan-oriented insurgents outside the scope of embedded mentoring and fire support.

• Dissolve the International Security Assistance Force (ISAF) and place Combined Forces Special Operations Component Command-Afghanistan (CFSOCC-A) in charge of the military mission by April 2013. This will be accompanied by a drawdown of US-NATO troop levels to a force of approximately 30,000 – 6,000-8,000 of whom should be non U.S. military personnel. This large drawdown will ensure that “ownership” is transitioned
to the Afghan state. The primary military mission will be to continue the intelligence and direct action campaign against transnational terrorist networks in the region.

• Full transition of governance and development efforts in Afghanistan to the United Nations by April 2013. Governance and development efforts do not aggregate to form an American political strategy.

• The United States and NATO allies will provide enduring material and political support to the Afghan state in order to ensure sufficient stability around Kabul, the north, and the west and prevent transnational terrorist networks from operating from Afghanistan.

Keeping more troops in Afghanistan through 2013 will not result in appreciable and durable gains in consolidating the Afghan government's hold over the country. Therefore, the costs in blood and treasure associated with a more gradual drawdown are simply not worth the meager gains they will deliver.
Link:http://cnponline.org/ht/a/GetDocumentAction/i/38128

I noted they recommend paying attention to how the USSR withdrew!